Photography And Half-Thoughts By Mitchell Hegman

Thursday, April 13, 2017

The Blood of Horseshoe Crabs

Horseshoe crab blood is
worth something. It’s worth quite a lot,
actually. A quart of horseshoe crab
blood has an estimated value of something near $15,000.

If you don’t know much
about horseshoe crabs, know this: the horseshoe crab you find today is pretty
much the same as the one you would find as a fossil from 450 million years
ago. They have not changed much. They didn’t need any kind of change to
survive.

They have good blood.

The blood of a horseshoe
crab is bright blue in color. The color
is a reflection of the fact that oxygen is carried using copper-based
hemocyanin. Our red blood uses iron in
hemoglobin for the same.

But the real trick is
what horseshoe crab blood does when confronted by bacteria. Where our blood might require a couple days
for white blood cells to muster a defense against the bacterial invaders, the
defensive amebocytes in horseshoe crab blood may successfully react in as
little as 45 minutes.

Over recent years,
biomedical researchers have been doing a great deal of life-saving work with horseshoe crab
blood. Some concern exists about
horseshoe crab populations. At one time
the crabs were over-harvested and destroyed to make fertilizer. In some areas, the crabs are still harvested
and used as bait. The horseshoe crabs
used in the biomedical industry are captured, bled, and released into the wild
again. Still, some question remains about the survival rate of the crabs
released into the wild again.